Method and apparatus for the production of music



Oct. 31, 1933.

C. T. JACOBS METHOD AND APPARATUS FOR THE PRODUCTION OF MUSIC iled Jan. 20, 1932 2 Sheets-Sheet 1 IN V EN TOR:-

c. T. JACOBS 1,933,294

METHOD AND APPARATUS FOR THE PRODUCTION OF MUSIC Oct. 31, 1933.

Filed Jan. 20, 1932 2 Sheets-Sheet 2 IN V EN TOR:-

Patented Oct. 31, 1933 METHOD AND APPARATUS FOR THE PRO- DUCTION OF MUSIC Charles T. Jacobs, New Providence Township,

Union County, N. J., assignor to Miossner Inventions, Inc., a corporation of New Jersey Application January 20, 1932. Serial No. 587,648

21 Claims.

This invention relates to methods and apparatus for, producing music from a plurality of tuned vibrators, and more specifically to methods and apparatus for producing music of which the tones are selectively controllable in respect of various characteristics. The invention contemplates a variety of methods of translating the vibrations of the tuned vibrators into sound e. g., direct mechanico-acoustic (vibrationsound) translation, simple mechanico-electroacoustic translation, and controlled-efficiency mechanico-electro-acoustic translation as disclosed and claimed in the co-pending joint applications of Benjamin F. Miessner and Charles T. Jacobs, Serial Numbers 538,773 and 558,207, filed May 20, 1931 and August 20, 1931, respectively (on which applications U. S. Patents 1,915,860 and 1,915,859 have now been issued).

Although useful with any form of vibrator and with any means for vibrating the same, the invention is illustrated with tuned strings caused to vibrate by percussion. Percussion excited strings, employed with direct mechanico-acoustic translation and coupled together by the translating system (c. g., by a bridge and soundboard), produce a piano type of tone. Employed with simple mechanico-electro-acoustic translation and coupled together, they produce generally a similar (piano) type of tone, subject, however, to a wider range of control in respect of harmonic structure, volume, etc. Again employed with simple mechanico-electro-acoustic translation, but not coupled together, they produce a tone somewhat different from piano tone, but suggesting description as a simple percussion tone (as lacking the peculiar characteristics of piano tone which result from the inter-string coupling). Employed with mechanico electro acoustic translation of which the efliciency is controlled coincidentally to excitation of the strings, they produce an organ or other type of tone, dependent on the nature of the efliciency control, as is fully described in the co-pending joint applications above referred to.

In these co-pending applications an instrument has been disclosed wherein the same vibrators were employed for the production of dif ferent types of tone. Such an arrangement suffers from the limitation that if the vibrators are coupled together, as may be necessary for the production of a piano type of tone for example, it is difficult to uncouple them for the production of a type of tone for which inter-vibrator coupling is not desirable (for example an organ tone, in which the increase in rate of damping brought about by the usual inter-vibrator coupling means is a detriment). It is furthermore difilcult with the same vibrators to employ selectively either mechanico-acoustic or mechanico-electro-acoustic translation at will, the avoidance of mechanico-acoustic translation when it is not intended to be efiective being a serious problem. I have also found that further interesting and unique types of tone may be created by producing jointly and coincidentally two or more tones of respectively different types, of which one may require the presence and another the absence of intervibrator coupling.

Accordingly it is a specific object of my invention to provide methods and apparatus for selectively producing, from a multi-vibrator musical instrument, two or more types of tone, of which one or more may require the presence, and one or more the absence, of inter-vibrator coupling. It is a further specific object to provide methods and apparatus for producing such two or more types of tone either selectively or jointly, at will. Another specific object of my invention is the provision of an improved multi-vibrator instrument-in which either mechanico-acoustic translation or mechanico-electro-acoustic translation may be selectively employed.

General objects of my invention are the provision of an improved multi-vibrator instrument in which are selectively employed a variety of methods of translation into sound of the vibrations of the vibrators, and the provision of a multi-vibrator instrument by which there may be produced selectively a variety of types of tone. Other and allied objects will more fully appear from the following description and the appended claims.

In the detailed description of my invention, hereinafter set forth, reference is had to the accompanying drawings, of which:-

Figure 1 is a plan view of a portion of an instrument embodying my invention in one form;

Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1, Figure 2 including certain electrical and electro-acoustic apparatus embodied in my invention; and

Figure 3 is a partial cross-sectional view illustrating a modified form of my invention.

In Figures 1 and 2 I show an embodiment of my invention in which are employed simple mechanico-electro-acoustic translation with intervibrator coupling, and controlled efiiciency mechanico-electro-acoustic translation without inter-vibrator coupling. The most general construc ion of the grand piano may be employed changes of particular features illustrated. A string 1 is provided for each note to be produced, strung for example from tuning pin 23 over ledge 39, under capo or pressure bar 3, around and in the groove of adjusting screw 4, around bridge pin 9, and over ledge 10 to hitch pin 5. Adjacent (illustrated in Figure 1 to the right of) the string 1 for each note to be produced may be provided a similarly tuned string 2. Each string 2 may be strung from a tuning pin 23, over ledge 39, under capo 3, around and in the groove of an adjusting screw 4' and to hitch pin 5'. In the arrangement shown each string 2 is longer than the similarly tuned string 1; and while I do not consider it imperative, I prefer to make the length ratios between the string 1 and the string 2 for each note practically a constant. To approximate normal similar tension on all the strings; each string 2 may be of lower mass per unit length than its similarly tuned string 1. It is convenient to have the string 1, and imperative to have the string 2, insulated from the plate of the instrument, which plate will be understood to include integrally the rear frame 6, capo 3, ledge 39 and the therewith contiguous front frame 40, etc.; this plate and its several portions may hereinafter be referred to as ground. Accordingly each hitch pin 5 may beset in an insulating bushing 12 and this in turn into rear frame 6; each hitch pin 5' and associated adjusting screw 4 may be mounted in a block '7 of insulating material, this in turn being secured to the rear frame 6; an insulating surface along the line of bearing of all the strings may be imparted to the bottom of capo 3 and to the top of ledge 39, for example in the form of strips of bakelite 8 having a cross-section ofan arc; and a similar insulating surface 13 may be provided over each ledge 10.

The adjusting screw 4 and bridge pin 9 engaged by each string 1 are mounted in a bridge 11, the function of which is to couple the strings 1 together. Bridge 11 may be mounted to a plurality of strips of wood 15, of small cross-section, running in general at right angles to the bridge, slightly arched toward it, and each secured at both extremities. Thus the forward ends of the strips 15 illustrated in Figure 1 are shown secured to rigid rim beam 38. This support for the bridge is both slightly vibratile and weakly coupled to the air; thus it effects coupling between the strings 1 without appreciably translating their vibration into sound.

For exciting the strings there may be provided hammers 18, actuated from keys 14 by the conventional grand piano action. As illustrated in Figure 1, each hammer is positioned to strike only the string 1 for each note. Means are provided, however, for shifting the hammers to the right, either slightly so that each strikes both a string 1 and the similarly tuned string 2, or further so that each strikes only a string 2. While a variety of well-known means and mechanisms for shifting the action of a grand piano are available, I have shown for simplicity of illustration a stud 81 screwed into the base 82 of the action, equipped with handle 83, and slidable in slot 84 in front bar or rail 85. The hammers may if desired be aligned from front to back to strike strings I at 1/7 to 1/8 of their active length behind their forward ends; this results in striking of strings 2 at a slightly smaller fractional position, due to the slightly greater length of strings 2. The usual dampers 19 may be provided, one

if desired, and has been assumed, subject to the for each note always operative on both strings I and string 2 for that note.

For translation into electric oscillations of the vibrations both of strings I and of strings 2, there are provided underneath the strings conductive strips 41 and 42, of small cross-section, each preferably cemented to the top edge of a thin bakelite or other insulating strip 43. The insulating strips 43 may be rigidly mounted to the rear frame 6 or to any other substantially nonvibratile support. The insulating strips may be so curved that the conductive strips lie under each string 1 at a point which similarly divides its active vibratory length from insulated capo 3 to adjusting screw 4-e. g., so that strip 41 lies under each string 1 at a point say 1/ 12th of its active length forward of adjusting screw 4 and so that strip 42 lies under each string 1 at l/7th of its active length forward of such screw. The proper spacing of the conductive strips from each string 1 and 2 is in general as small as possible without causing contact between the two under conditions of maximum vibration of the string; accurate adjustment of this spacing is facilitated by use of the adjusting screws 4 and 4'.

Each conductive strip may be electrically connected to ground through a high resistance, shown in Figure 2,'as 50 and 51 for strips 41 and 42, respectively, and also to the grid of a thermionic vacuum tube, shown as 47 and 48, respectively. The cathodes of these tubes may be energized in any suitable manner, as by battery 49; their anode current may be supplied as by a tap 55 on battery or other source 65, the negative terminal of which may be connected to ground. The cathodes of these tubes may be connected to ground through a condensively by-passed resistance 52, for the biasing of their grids negatively with respect to the cathodes by virtue of anode current flow through such resistancefas will be understood. In the output circuit of tube 47 may be provided transformer 53 and in the output circuit of tube 48 may be provided transformer 54. Across the secondary of transformer 53 may be connected center-tapped potentiometer 57 and across the secondary of transformer 54 potentiometer 56. In series with adjustable portions of each of these potentiometers, as shown, may be provided potentiometer 58, preferably of higher resistance; and across an adjustable portion of potentiometer 58 may be connected electrical amplifier 59 feeding into loudspeaker 60. Electrostatic shielding 61, at ground potential, may advantageously be provided about the strips 41 and 42, about the tubes 47 and 48 and associated apparatus, about the leads to their grids, etc.

If now any string or strings 1 and/or 2 be established at a different D. C. potential from ground, the minute capacities between such string or strings and the conductive strips 41 and 42 will be charged to the value of such D. C. potential difference. If the string or strings be vibrating these capacities will vary oscillatorily in accordance with the frequency and waveform of the portions of such string or strings immediately above the strips. The charges will be seen to be introduced into these capacities through the respective resistances 50 and 51, and by virtue of the high values of the latter the charges are maintained relatively unchanged by the oscillatory capacity variations, which variations therefore result in corresponding variations in the voltage across the capacities. These variations comprise A. C. voltages whose amplitude varies directly with the mean D. 0. potential across the capacities; and these A. C. voltages appear of course across the respective resistances 50 and 51 and at the input of tubes 47 and 48. By these tubes and the transformers such voltages are amplifled; and they therefore appear in amplified form across the potentiometers 56 and 57. By adjustment of the latter any fraction of the voltage across the secondary of transformer 54 (derived from strip 42), and any fraction up to half, in either of two phases, of the voltage across the secondary of transformer 53 (derived from strip 41), may be applied to potentiometer 58. The combined voltages may be regulated in respect of amplitude by potentiometer 58, and thereafter amplified by amplifier 59 and translated into sound by loudspeaker 60.

The function of the plurality of translating systems (each comprising a conductive strip, tube, transformer and associated apparatus) is to provide variation of harmonic structure of the translated A. C. voltages, or electric oscillations, as is disclosed in U. S. Patent Number 1,906,607, issued to me May 2, 1933. This control arises from the diff aence in waveform of the vibration of the portion, of each string respectively above strips 41 and 42, the consequent difference in harmonic structure of the oscillations derived respectively from the two strips, and the infinite number of amplitude relationships and dual phase relationships in which these oscillations may be combined by the potentiometers. It will be understood of course that if harmonic structure variation be not desired, one of the conductive strips, one of the tubes, one of the transformers and one of the potentiometers, etc., may be omitted; conversely, that if wider variation in harmonic structure than is available with two translating systems be desired, a larger number than two may be employed with appropriate combining controls.

It has been pointed out above that the amplitude of the oscllations translated from the vibration of any string will vary directly with the mean D. C. potential difference between that string and ground; in other words it may be said that the efliciency of translation is dependent on such D. C. potental difference. In the production of a piano type of tone from coupled, percussion-excited strings, it is obviously desirable that the efficiency of translation be maintained constant throughout the duration of any part'cular tone or tones, excepting when special effects are desired. Therefore I have shown all the strings 1, which engage bridge 11 and are thereby coupled together, electrically connected together and through switch 74 (in. its down-most position) to a potential positive with respect to ground-i. e., to the positive terminal of battery or source (of which the negative is grounded). If now the hammers 18 be positioned to strike only the strings I and the nstrument be played, a piano type of tone will be produced in loudspeaker 60, subject to control in respect of tone harmonic structure by the potentiometers 56 and 57.

For the production of organ and certain other types of tone from percussion-excited strings or other vibrators, it is desirable that the vibrators be uncoupledhence the provision of strings 2. For certa'n of these types of tones, including organ. it is furthermore necessary that the efficiency of translation of the vibration of each vibrator be varied coincidentally to excitation. Accordingly I have shown certain arrangements and circuits for suitably varying the D. C. potential of each string 2 with respect to ground, which arrangements and circuits themselves have been largely dsclosed and claimed in the co-pending joint applications hereinabove referred to.

Thus each string 2 may be electrically connected, as for example, by its tuning pin 23, through a separate condenser .20 to ground. Each string 2 may further be connected through a separate resistor 21 to a lug 25 on the flange 24 of the hammer which str.kes that string. To each lug 25 may be connected a separate resistor 2'7 and a separate condenser 26. The other sides of all the resistors 27 may be wired together to form a common electrical connection M; and the other sides of all the condensers 28 may be wired together to form a common electrical connection N.

Across each condenser 26 is provided a switch 36, arranged to be closed just after an impact of the associated hammer with the associated string produced by depression of the associated key, and arranged to be opened upon release of such key. Although more than one arrangement in and about the hammer action may be employed to act as such a switch, I have employed the hammer-tail 17 and the associated back-check 16 as the two mechanical elements of the switch 36, equipping each of them at and near its region of contact to theother with a metal strip'. Such metal may be covered by a thin piece of chamois or other leather, impregnated with a colloidal graphite solut'on; or by some other relatively soft but conductive material. Thus to each hammer-tail 17 may be glued or otherwise fastened metal strip 28; and impregnated leather strip 29 may be glued or otherwise fastened, preferably at or near its extremities only, to metal strip 28. In sim'lar manner over the customary felt 30 of each back-check 16 may be glued or otherwise fastened metal strip 31; and impregnated leather strip 32 may be glued or otherwise fastened, preferably at or near its extremities only, to metal strip 31. Each strip 28 may be wired, as by a fine wire, to a lug 33 on the hammer stem near its p'vot, and the lug 33 in turn connected as by flexible connection 34 to the associated lug 25. All strips 31 may be connected together, as by loose flexible connections 35, and to common electrical connection N. The common connections M and N may be wired to the poles 62 and 63 respectively of double pole switch 64.

It will now be assumed that the hammer action has been sh fted so that strings 2 and not strings 1 are struck. With the poles of switch 64 connected to. their upmost contacts, as shown, connection M is rendered at ground potential and connection N at the potential of the positive of battery or source 65. By virtue of its connection to point M through res'stors 21 and 27, each string 2 is also at ground potential. The efficiency of translation is therefore zero and, were the string to be in a state of vibration, no A. C. voltage would be produced thereby at the grid of either tube 4'7 or 48. If now one of the keys 14 be depressed, its damper 19 w'll be lifted from the associated string 2; and its hammer 18 will be propelled toward and caused to strike the string, setting the latter into vibration. The hammer 18 will immediately rebound from the strng and, unless the blow be an extreme, incomplete stacatto, the leather surface 29 on the hammer-tail 1'? will be driven into contact with and will frictionally engage the leather surface 32 of the back-check 16, now occupying a raised position, as will be understood by those skilled in the piano art. Otherwise expressed, the switch 36, comprising the metal strips 28 and 31 and the conductive leather strips 29 and 32, will be closed just after impact of the hammer 18 and string 2.

It will be seen that upon closing of switch 36 the associated condenser 26 will begin to discharge through the residual (closed) resistance of the switch and current will begin to flow through the switch and resistance 27 from the positive to the negative terminal of battery or source 65. This causes the potential of lug 25 to rise and the condenser 20 to charge thereirom through resistance 21, thus in turn raising the potential 01. the string 2. The rise of potential oi the string will be gradual, rather than instantaneous, since it requires'time for the condenser 26 to discharge through the residual resistance of switch 36 and for condenser 20 to charge through resistance 21. Thus the efliciency of translation into electric oscillations of the vibration of string 2 will rise gradually, rather than abruptly, at a rate determined by the electrical values of the circuit components. The vibration of a string 2, produced by the impact 01' a hammer 18 therewith immediately preceding the closing of switch 36, therefore begins to produce an A. C. voltage at the grid of each of the tubes 4'7 and 48, and hence a tone in loudspeaker 60, just after the impact; and these voltages and tone rise in amplitude according to the rate of rise of potential between the string and frame. The limit to which the potential difl'erence, and hence the translation efficiency and loudspeaker output, may rise is of course determined by the voltage of battery or source 65, and by therelative values of resistance 27 and residual resistance of switch 36.

Thus with the setting of switch 64 in the upmost position the tone starting characteristics of the organ and similar instruments are simulated. No impact component in the tone is produced, since impact of hammer and string occurs while translation efficiency for that string is still zero; and the amplitude of the tone rises gradually, rather than abruptly, simulating the gradual rise of tone from a wind-operated pipe. In order that the tone continuation characteristics may as closely as possible simulate those of the organ or other tone-sustaining instrument. it is important that the string bearings at front and back of the active vibratory length of the string-4. e., insulating strip 8 and adjustingscrews 4--be mounted as rigidly as possible, in order that a minimum absorption of the energy of the string by its supports take place, thus reducing to a minimum the inherent rate of damping of the strings 2. Tone termination characteristics are established principally by the drop to zero of potential between the string and framei. e., of translating efiiciency-due to opening of switch 36, which will be understood by those skilled in the art to occur at the beginning of the release of key 14; but suitably rapid termination is aided by the return to contact with the string of damper 19, which occurs just before the completion of key release.

With the poles of switch 64 connected to their middle contacts, common connection M may be rendered at the potential of a tap 67 on battery or source and common connection N may be connected to the slider 68 of potentiometer 69 shunting battery 65, by which slider the potential of N may-be made equal to, or lower or higher than, the potential of M. These three respective adjustments of the slider 68 may be shown to produce respectively simple percussion tone, such tone with extra amplitude decrease just aiter tone inception, or such tone with at least a tendency toward amplitude increase just after tone inception. It is to be noted that in the first of these cases simple mechanica-electro-acoustic translation is being effected, efliciency control being absent as a result of lack of potential difference between common connections M and N.

The length of time elapsing between the inception of a tone and the attainment thereby of sensibly full volume when switch 64 is in the upmost position, or between the inception of a tone and the attainment thereby 0! its reduced or increased volume when switch 64 is in the middle position, may be fixed at any desired value by suitable choice of the values of the several components of the circuit associated with each string 2. If desired, such length of time may be variously established for difl'erent notes of the instrument by differentiation of the values of one or more of the components between the circuits associated with the several strings 2. It will of course be understood that various modifications may be made in the internal arrangement of the several circuits without altering their fundamental action. I have found it satisfactory, however, to employ for each string 2 the circuit illustrated, with values of components of the order tabulated below:--

Condenser 20. .05 microfarads Resistance 21, 1 mcgolim Condenser 26. .1 microfarad Resistance 27, megohm and to employ leather strips 29 and 32 in the switches 36 impregnated with colloidal conductive solution of proper strength to yield switches having a residual, or closed, resistance of approximately 50,0Q0 ohms.

I have thus far disclosed among other things coupled strings with simple. mechanico-electricacoustic translation, uncoupled strings with both simple and controlled-efllciency mechanico-electro-acoustic translation, and mechanical (actionshifting) means for selectively producing music from either set of strings. rangements may be employed, however, in substitution for and/or in addition to the mechanical selective means. Thus when translation from strings 2 only is desired, translation from strings 1 may be avoided not only by failure to strike them by hammers 18, but also or alternatively by connecting strings 1 to ground by throwing switch 74 to its up-most position. Likewise when translation from strings 1 only is desired, translation from strings 2 may be avoided not only by failure to strike them, but also or alternatively by throwing switch 64 to its down-most position, grounding both common connections M and N. Thus if desired the hammer action may be employed always to strike both strings I and 2 for 1'- each note and the selection effected by electrical means. Further, with the hammers striking both strings, new types of tone may be created by translation both from strings 1 and at the same time from strings 2, translation from the latter being itself adjusted by switch 64 and movable contact 68 to produce from these strings any of the several mentioned types of tone. In this case the relative prominence of the contributions of Other selective arthe strings l and 2 to the composite tone may be 1 regulated as by throwing switch 74 to its middle position and adjusting the D. C. potential applied to strings I by means 01' another movable contact '78 on potentiometer 69. It will be understood, of course, that any two or more of the electrical switches and the voltage adjusting and hammer-action shifting controls may be suitably interlinked to reduce the number of controls in any given case, for the selective production of any particular group of eflects.

Various modifications may of course be made in the arrangements and apparatus thus far disclosed. Thus for example efliciency control may be employed in connection with translation from the coupled strings I as well as from the uncoupled strings 2. Again, strings 2 may be of the same active length as strings I, thus avoiding appreciable difference of harmonic structure in the oscillations translated, with any given setting of potentiometers 56 and 57, from strings 1 and 2. With the greater length of strings 2 as shown, the reduced proximity of the conductive strips 41 and 42 to the ends of strings 2, and the consequent greater predominance of lower partials in the tones produced by strings 2, I have at times found it desirable to provide another conductive strip such as 41', positioned longitudinally along the strings 2 in approximately the same relative position as that occupied by strip 41 along strings 1. This strip 41' will not be-active with respect to strings I; but will be with respect to strings 2 when substituted for or paralleled with strip 41, as by switch 79.

In Figure 3 I show a fractional cross-sectional view intended for substitution for the upper righthand portion of Figure 2, to illustrate a modification of my invention. The changes are the inclusion of a resonator orsoundboard afiixed to the bottom of bridge 11 and the top of strips 15, the omission of insulation 12 and 13 for strings 1 and of electrical connection to strings 1, and the substitution of a conventional bridge pin 9 for adjusting screw 4. Thus there is provided an instrument wherein direct mechanico-acoustic translation alone may be effected by soundboard 80 (the hammers striking only strings 1) or either simple or controlled efficiency mechanico-electroacoustic translation effected (the hammers striking only strings 2); or both mechanico-acoustic and simple or controlled efiiciency mechanicoelectro-acoustic translation simultaneously effected (the hammers striking both strings 1 and strings 2). Thus a combined organ (producing sound through loudspeaker 60) and conventional acoustic piano (producing sound from its soundboard) may be made; or a combined electrical and acoustic piano, etc. Of course more than one string 1 may be used per note if desired to increase the output of such an acoustic piano, the hammers being shiftable so that each strikes all its strings 1, or its strings 2, or simultaneously its string 2 and one or more of its strings I.

It will finally be appreciated that in such respects as the invention concerns selective. and other mechanico-electro-acoustic translations, no limitation is intended whereby novel selective and other mechanico-electric translations might be impliedly disclaimed.

I claim:

1. In a musical instrument, the method of selectively producing output tones of different characteristics, which consists in vibrating simultaneously a plurality of similarly tuned vibrators, and in selectively efiecting qualitatively different translations into sound of the respective vibrations of the several said vibrators.

2. In a musical instrument, the method of selectively producing output tones of difierent characteristics, which consists in effecting qualitatively difierent translations into sound of the respective vibrations of a; plurality of similarly tuned vibrators, and in selectively producing said vibrations of the several said vibrators.

3. In a musical instrument, the method of selectively producing output tones of different characteristics, which consists in vibrating simultaneously a plurality of similarly tuned vibrators, in effecting qualitatively different translations into sound of the respective vibrations of the several said vibrators, and in selectively adjusting the relative efliciencies of the translations from the several said vibrators.

4'. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; a plurality of means, each common to correspondingly tuned vibrators in the several sets, for vibrating said vibrators;- means for translating the vibrations of the vibrators of the respective sets into sounds of substantially different characteristics; and means connected with said vibrating means and adjustable at will to control the action thereof selectively with respect to the several sets.

5. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means for translating the vibrations of the vibrators of the respective sets into sounds of substantially different characteristics; and means connected with said translating means and adjustable at will to control the operation thtereof selectively with respect to the several se 5.

6. In a musical instrument, the combinationof a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means for translating sounds of substantially different characteristics from the vibrations of the vibrators of the respective sets; and selectively adjustable means connected with said translating means for controlling the relative efiiciencies of such translations from the several sets.

'7. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets, and the vibrators of the respective sets having substantially different vibrational characteristics; a plurality of means, each common to correspondingly tuned vibrators in the several said sets, for vibrating said vibrators; means for translating the vibrations of all of said vibrators into sound; and means connected with said vibrating means and adjustable at will to control the action thereof selectively with respect to the several sets.

8. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets,

and the vibrators of the respective sets having substantially diiferent vibrational characteristics; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means for translating the vibrations of all 01 said vibrators into sound; and means connected with said translating means and adjustable at will to control the operation thereof selectively with respect to the several sets.

9. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets, and the vibrators of the respective sets having substantially different vibrational characteristics; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means for translating sound from the vibrations of all of said vibrators; and selectively adjustable means connected with said translating means for controlling the relative efllciencies of such translations from the several sets.

10. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; a plurality of means, each common to correspondingly tuned vibrators in the several sets, for vibrating said vibrators; resilient means engaging the vibrators of at least one but less than all of said sets, whereby different damping rates are imparted to the vibrators of respectively different sets; means for translating the vibrations of all of said vibrators into sound; and means connected with said vibrating means and adjustable at will to control the action thereof selectively with respect to the several sets.

11. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; resilient means engaging the vibrators of at least one but less than all of said sets, whereby diiIerent damping rates are imparted to the vibrators of respectively different sets; means for translating the vibrations of all of said vibrators into sound; and means connected with said translating means and adjustable at will to control the operation thereof selectively with respect to the several sets.

12. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; a plurality of means, each common to correspondingly tuned vibrators in the several sets, for vibrating said vibrators; means coupling to other vibrators of the same set each vibrator in at least one but less than all of said sets; means for translating the vibrations of all of said vibrators into sound; and means connected with said vibrating means and adjustable at will to control the action thereof selectively with respect to the several sets.

13. In a musical instrument, the combination of a plurality of sets of vibrators, each set compris ing a plurality of vibrators respectively tuned in correspondence with those of the other sets; means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means coupling to other vibrators of the same set each vibrator in at least one but less than all of said sets; means for-translating the vibrations of all of said vibrators into sound; and means connected with said translating means and adjustable at will to control the operation thereof selectively with respect to the several sets.

14. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets;

a plurality of meansfeach common to correspondingly tuned vibrators in the several sets, for vibrating said vibrators: means for translating the vibrations of all of said vibrators into sound; means connected with said vibrating means and adjustable at will to control the action thereof selectively with respect to the several sets and means, co-acting with said vibrating means, for varying the efiiciency of such translation of the vibration of each vibrator in at least one but less than all of said sets.

15. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets;

.means simultaneously vibrating correspondingly tuned vibrators in a plurality of said sets; means for translating the vibrations of all of said vibrators into sound; means connected with said translating means and adjustable at will to control the operation thereof selectively with respect to the several sets; and means, co-acting with said vibrating means, for varying the efficiency of such translation of the vibration of each vibrator in at least one but less than all of said sets.

16. In a musical instrument, the combination of a plurality of sets of vibrators, each set comprising a plurality of vibrators respectively tuned in correspondence with those of the other sets; a plurality of means, each common to correspondingly tuned vibrators in the several sets, for vibrating said vibrators; mechanico-acoustic apparatus for translating directly into sound vibrations of the vibrators of at least one but less than all of said sets; mechanico-electro-acoustic translating apparatus for translating into electric oscillations and thence into sound vibrations of the vibrators of at least one other of said sets; and means connected with said vibratingmeans and adjustable at will to control the action thereof selectively with respect to the several sets.

17. A combined acoustic and electric piano, including two sets of strings,each set compris ing a plurality of strings respectively tuned in correspondence with those of the other set; a resonator coupled to the strings of one set; mechanico-electro-acoustic translating apparatus for translating into electric oscillations and thence into sound vibrations of the strings of the other set; a plurality of means, each common to correspondingly tuned strings in the two sets, for exciting said strings; and means connected with said exciting means and adjustable at will to control the action thereof selectively with respect to said two sets.

18. A combined acoustic piano and electric organ, including two sets of strings, each set comprising a plurality of strings respectively tuned in correspondence with those of the other set; a resonator coupled to the strings of one set; mechanico-electro-acoustic translating apparatus for translating into electric oscillations and thence into sound vibrations of the strings of the other set; a plurality of means, each common to correspondingly tuned strings in the two sets, for exciting said strings; means connected with said exciting means and adjustable at will to control the action thereof selectively with respect to said two sets; and means, co-acting with said exciting means, for varying the efficiency of said mechanico-electric-acoustic translation of vibration of each string of said other set.

19. A combined electric piano and organ, including two sets of strings, each set comprising a plurality of strings respectively tuned in correspondence with those of the other set; a plurality of means, each common to correspondingly tuned strings in the two sets, for exciting said strings; means connected with said exciting means and adjustable at will to control the action thereort selectively with respect to said two sets; mechanico-electric translating apparatus for translating into electric oscillations vibrations of all of said strings; means coupling together the strings of one set; and means, co-acting with said exciting means, for varying the efliciency of such translation of vibration 01' each string of the other set.

20. A combined electric piano and organ, including two sets of strings, each set comprising a plurality of strings respectively tuned in correspondence with those of the other set; means simultaneously vibrating correspondingly tuned strings in the two sets; mechanico-electric trans-' lating apparatus for translating into electric oscillations the vibrations of all of said strings; means connected with said translating apparatus and adjustable at will to control the operation thereof selectively with respect to said two sets; means coupling together the strings of one set; and means, co-acting with said exciting means, for varying the efllciency of such translation of vibration of each string of the other set.

21. In a musical instrument, the combination of a tuned vibrator, means for translating sound from the vibration thereof, percussive exciting means therefor, co-acting means for producing electric oscillations of gradually rising initial amplitude and of frequency similar to that of said vibrator, and means for translating sound from said oscillations.

CHARLES T. JACOBS. 

